This invention relates to an apparatus in which are incorporated, in combination, a reader for cards, microfiches, or microfilms and a copying system.
The practice of using reader-printer apparatus comprising the combination of a copying system and a reader has become popular in recent years. This is an increasing demand for reader-printer apparatus of the type which permits an original either in the form of a negative or in the form of a positive to be selectively handled. In one type of reader-printer apparatus known in the art, the charger is switched between opposite charging polarities for effecting switching between positive and negagive. To effect switching between opposite charging polarities, it is necessary to use a complex construction for moving the charger casing upside down or to utilize a high voltage change-over switch.
Copying systems of the prior art have the disadvantage of having to adjust the charging condition each time the quality of paper handled is varied, e.g. between translucent paper and ordinary paper, or there is a change in the size of the copy sheets required, in order to produce duplicates of high quality. Thus they are inconvenient to operate.
For example, microfilm used as an original is either in a negative form or positive form. Users may wish to use an original in either negative form or positive form as desired. In one type of printers or copying systems known in the art, a positive image can be obtained from both negative and positive originals by switching between the opposite charging polarities of the copy sheets. Besides producing duplicates of an original by using ordinary copy sheets, the need arises of using translucent paper for file copies of drawings and for use in the design section. To meet this requirement, proposals have been made by us to provide a reader-printer apparatus which is capable of using translucent paper.
However, there has been no reader-printer apparatus available which enables obtaining duplicates of high quality by switching by simple means regardless of the type of an original, for example, whether it is negative or positive, and the type of copy sheets.